Self-assembled molecules electrostatics

The CD-based polycations have been synthesized for nucleic acid delivery. Upon mixing them with nucleic adds, the polymers and nudeic acids self-assemble by electrostatic interactions to give nanoparticles, i.e. polyplexes. Polyplexes are able to transfect cultured cells with high effidency and relatively low toxidty. Moreover, CDs on the surface of polyplexes can form inclusion complexes with hydrophobic guest molecules. 

The following sections contain a review of many of the varied synthetic systems that have been developed to date utilising noncovalent interactions to form assembhes of molecules. These sections are loosely demarcated according to the most important type of noncovalent interactions utilized in conferring supramolecular order (ie, van der Waal s interactions, electrostatic interactions, and hydrogen bonds). For extensive reviews, see References 1,2,4—6,22,46,49,110—112. Finally, the development of self-assembling, self-replicating synthetic systems is noted. 

Niece KL, Hartgerink JD, Donners J et al (2003) Self-assembly combining two bioactive peptide-amphiphile molecules into nanofibers by electrostatic attraction. J Am Chem Soc 125 7146-7147... 

The electrostatic forces also play an important role in the conformation and structure of macromolecules such as polymers, polyelectrolytes, and proteins. The self-assembly of proteins from disks to virus is triggered by electrostatic interactions between neighboring subunits. In the case of polyelectrolytes (polymer molecules with charges) and charged colloids, transport behavior such as rheology is also affected significantly by charge effects, as we have already seen in Chapter 4. 

Surface science has been one of the first beneficiaries of self-assembled nanostructures (in the form of SAMs). Self-assembly is a very general strategy for forming molecularly tailored interfaces, and, other than the few systems that have formed the basis for the majority of work in SAMs, almost none of the obvious opportunities to use self-assembly to build ordered, nanostructured interfaces have been examined. The preparation of more sophisticated structures based on molecules with complex stmctures, on self-assembled colloids, on multilayered polymers formed by electrostatic interactions between charged groups166,167, or on biologically derived structures is just beginning168-171. 

Another type of noncovalent interaction, namely electrostatic ones, has recently been exploited by Wang et al. in the fabrication of a hybrid film containing a water-soluble poly(thiophene) derivative and CdSe NCs.141 In this case CdSe NCs were functionalized with 11-mercaptoundecanonic acid (MUA) molecules prior to their self-assembly with side chain-functionalized poly(thiophene), that is, poly(3-(3 -thienyloxy)propyltrimethylammonium bromide) (P3TOPA). 

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